System to improve coreless package connections and associated methods

ABSTRACT

A system to improve core package connections may include ball grid array pads, and a ball grid array. The system may also include connection members of the ball grid array conductively connected to respective ball grid array pads. The system may further include magnetic underfill positioned adjacent at least some of the connection members and respective ball grid array pads to increase respective connection members&#39; inductance.

BACKGROUND

A ball grid array (“BGA”) may be a surface mount package carrying anintegrated circuit and connections members. The connections members areusually coupled to ball grid array pads carried by a printed circuitboard.

A coreless package is a type of integrated circuit package that may haveno rigid epoxy core. The coreless package usually includes analternating layered substrate having insulating layers separated bypatterned conductor layers.

SUMMARY

According to one embodiment, a system to improve core packageconnections may include ball grid array pads, and a ball grid array. Thesystem may also include connection members of the ball grid arrayconductively connected to respective ball grid array pads. The systemmay further include magnetic underfill positioned adjacent at least someof the connection members and respective ball grid array pads toincrease respective connection members' inductance.

The magnetic underfill may include resin mixed with magnetic materials.The resin may include epoxy and the magnetic material may includeferrite powder and/or ferromagnetic materials. The mixture may beselected based upon a desired permeability.

The magnetic underfill may be applied based upon the ball grid array'sheight after collapse. The resin may have a glass temperature higherthan the ball grid array's reflow temperature so flow of the resin canbe controlled during reflow.

The system may include resin and/or resin mixed with dielectric constantmaterials positioned where the magnetic underfill is undesirable. Theball grid array may be carried by a coreless package.

Another aspect is a method to improve core package connections. Themethod may include positioning magnetic underfill adjacent at least someof connection members of a ball grid array and respective ball gridarray pads to increase the connection members' inductance. The methodmay also include conductively connecting the connection members of theball grid array to respective ball grid array pads.

The method may further include applying the magnetic underfill basedupon the ball grid array's height after collapse. The method mayadditionally include mixing resin with magnetic materials based upon adesired permeability to produce the magnetic underfill.

The method may also include selecting at least one of ferrite powder andferromagnetic materials for the magnetic material. The method mayfurther include controlling the flow of the resin during reflow byselecting for the resin a glass temperature higher than the ball gridarray's reflow temperature.

The method may also include positioning at least one of a resin andresin mixed with dielectric constant materials where the magneticunderfill is undesirable. The method may further include curing themagnetic underfill using at least one of thermal curing, infraredcuring, and ultraviolet curing. The method may additionally includecleaning any residue from the ball grid array' exposed surface after theconductive connection.

In one embodiment, the system may include ball grid array pads, acoreless package, and a ball grid array carried by the coreless package.The system may also include connection members of the ball grid arrayconductively connected to respective ball grid array pads. The systemmay further include magnetic underfill positioned adjacent at least someof the connection members and respective ball grid array pads toincrease respective connection members' inductance, and the magneticunderfill is applied based upon the ball grid array's height aftercollapse.

In another embodiment, the system may include ball grid array pads, acoreless package, and a ball grid array carried by the coreless package.The system may also include connection members of the ball grid arrayconductively connected to respective ball grid array pads. The systemmay further include magnetic underfill positioned adjacent at least someof the connection members and respective ball grid array pads toincrease respective connection members' inductance. The system mayadditionally include resin and/or resin mixed with dielectric constantmaterials positioned where the magnetic underfill is undesirable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic block diagram of a prior art BGA pad connected toa chip package.

FIG. 2 is a prior art time domain reflectometer graph.

FIG. 3 is a prior art package substrate.

FIG. 4 is another embodiment of a prior art package substrate.

FIG. 5 is a schematic block diagram of a system to improve core packageconnections.

FIG. 6 is a schematic block diagram of another embodiment of the systemof FIG. 5.

FIG. 7 is a schematic block diagram of another embodiment of the systemof FIG. 5.

FIG. 8 is a flowchart illustrating method aspects according toembodiments of the invention.

FIG. 9 is a flowchart illustrating method aspects according to themethod of FIG. 8.

FIG. 10 is a flowchart illustrating method aspects according to themethod of FIG. 8.

FIG. 11 is a flowchart illustrating method aspects according to themethod of FIG. 6.

FIG. 12 is a flowchart illustrating method aspects according to themethod of FIG. 10.

FIG. 13 is a flowchart illustrating method aspects according to themethod of FIG. 10.

FIG. 14 is a flowchart illustrating method aspects according to themethod of FIG. 10.

FIG. 15 is a flowchart illustrating method aspects according to themethod of FIG. 10.

DETAILED DESCRIPTION

The embodiments will now be described more fully hereinafter withreference to the accompanying drawings. Like numbers refer to likeelements throughout, like numbers with letter suffixes are used toidentify similar parts in a single embodiment, letter suffix lower casen indicates any unused letter, and prime notations are used to indicatesimilar elements in alternative embodiments.

It should be noted that in some alternative implementations, thefunctions noted in a flowchart block may occur out of the order noted inthe figures. For example, two blocks shown in succession may, in fact,be executed substantially concurrently, or the blocks may sometimes beexecuted in the reverse order, depending upon the functionalityinvolved.

With reference now to FIGS. 1 and 2, in the prior art, extra capacitance13 a-13 b may be associated with a BGA pad 11 that may introduceimpedance discontinuity 15 that cause detrimental signal effects. Theimpedance discontinuity 15 is illustrated by a time domain reflectometergraph of the detrimental signal effects.

With additional reference to FIG. 3, a prior art package is illustratedin which a portion of the BGA pad 11 are overlapped by power supply 17and/or ground 19. As a result, there can be significant impedancediscontinuity in the prior art package and this problem becomes greateras the signal speed increases.

One prior art solution to the preceding, which is illustrated in FIG. 4,is to remove the overlap between the BGA pad 11 and the power supply 17and/or the ground 19. However, removing the overlap may weaken themechanical strength of the package and it may impact routingcapabilities and power integrity of the package. Additionally, theforegoing design will not work with coreless packages because of thecoreless package's lack of a thick core that can reduce the BGA padcapacitance.

A coreless substrate for use in a semiconductor package may contain nocore made of relatively rigid glass epoxy. The coreless substrate mayinclude a build-up substrate, e.g. surface laminar circuit substratecomposed of alternatively stacked insulating layers and patternedconductor layers. A package obtained by mounting a semiconductor chip onthe coreless substrate is generally called a coreless chip package.

A conventional coreless package may have a mounted semiconductor chipthat electrically connects with an electrode pad on the surface of thesubstrate. The space between the surface of the substrate and thesemiconductor chip is usually filled with an underfill made of a resinmaterial. A stiffener made of a resin material may be arranged aroundthe semiconductor chip on the substrate. The coreless substrate, havingno rigid core, is lower in stiffness than a substrate with a core. Theresin stiffener is provided for the purpose of compensating for such lowstiffness of the substrate. A ball grid array (BGA) may be used forelectrically connecting the substrate to another substrate. In anyconfiguration a BGA and its respective BGA pads have to be withinjoining distance of each other.

To address the problems described above, a system 10 to improve coredand coreless package connections is initially described that willimprove signal integrity of high-speed signals by minimizing theimpedance discontinuity from the BGA and BGA pads and/or the like.

With additional reference to FIGS. 5 and 6, according to one embodiment,the system 10 includes ball grid array pads 12 a-12 n, and a ball gridarray 14. In one embodiment, the system 10 includes connection members16 a-16 n of the ball grid array 14 conductively connected to respectiveball grid array pads 12 a-12 n. In another embodiment, the system 10includes magnetic underfill 18 a-18 n positioned adjacent at least someof the connection members 16 a-16 n and respective ball grid array pads12 a-12 n to increase respective connection members' inductance.

In one embodiment, the magnetic underfill 18 a-18 n includes resin mixedwith magnetic materials. In another embodiment, the resin includesepoxy, and the magnetic material includes ferrite powder and/orferromagnetic materials. In one embodiment, the mixture is selectedbased upon a desired permeability for the magnetic underfill 18 a-18 n.In one embodiment, system 10 adds inductance to balance capacitance sothat impedance discontinuity will be reduced. For example, inductance isproportional to the permeability of its environment and system 10controls the permeability of the underfill to achieve the optimalperformance.

In another embodiment, the magnetic underfill 18 a-18 n is applied basedupon the ball grid array's 14 height after collapse. For instance,collapse means the connection medium, e.g. solder, is melted to form theBGA connections with the BGA pads. In addition, by the selection of anappropriate connection medium and by managing the application of heat,the collapse of the BGA can be controlled.

In one embodiment, the resin has a glass temperature, e.g. meltingpoint, higher than the ball grid array's 14 reflow temperature so flowof the resin can be controlled during reflow. For example, “reflow”usually means melting the resin to form connections while minimallyimpacting the BGA connection medium connections. In one embodiment, thereflow temperature matters and system 10 controls the location of themagnetic underfill when the resins are melted.

With additional reference to FIG. 7, in another embodiment, the system10″ includes resin and/or resin mixed with dielectric constant materials21 a″-21 n″ positioned where the magnetic underfill 18 a″-18 n″ isundesirable such as in the power supply area to provide increasedcapacitance for the power supply. In one embodiment, the ball grid array14″ is carried by a coreless package 20″.

Another embodiment is a method to improve core package connections,which is now described with reference to flowchart 22 of FIG. 8. Themethod begins at Block 24 and may include positioning magnetic underfilladjacent at least some of connection members of a ball grid array andrespective ball grid array pads to increase the connection members'inductance at Block 26. The method may also include conductivelyconnecting the connection members of the ball grid array to respectiveball grid array pads at Block 28. The method ends at Block 30.

In one embodiment, high speed signals may be adversely affected by theextra capacitance from the BGA pads, so system 10 will have magneticunderfill in areas with high speed signals (e.g., signals in thegigahertz frequency range). In another embodiment, adding extrainductance may not be desirable to some signals or power BGAs, butsystem 10 will have magnetic underfill for all areas if it is deemedeasier to construct and the disadvantage to some signal/power lines istolerable.

In another method embodiment, which is now described with reference toflowchart 32 of FIG. 9, the method begins at Block 34. The method mayinclude the steps of FIG. 4 at Blocks 26 and 28. The method mayadditionally include applying the magnetic underfill based upon the ballgrid array's height after collapse at Block 36. The method ends at Block38. For instance, inductance and extra inductance is related to theheight, and to achieve the best performance, these parameters need to beconsidered.

In another method embodiment, which is now described with reference toflowchart 40 of FIG. 10, the method begins at Block 42. The method mayinclude the steps of FIG. 4 at Blocks 26 and 28. The method mayadditionally include mixing resin with magnetic materials based upon adesired permeability to produce the magnetic underfill at Block 44. Themethod ends at Block 46.

In another method embodiment, which is now described with reference toflowchart 48 of FIG. 11, the method begins at Block 50. The method mayinclude the steps of FIG. 6 at Blocks 26, 28, and 44. The method mayadditionally include selecting at least one of ferrite powder andferromagnetic materials for the magnetic material at Block 52. Themethod ends at Block 54.

In another method embodiment, which is now described with reference toflowchart 56 of FIG. 12, the method begins at Block 58. The method mayinclude the steps of FIG. 6 at Blocks 26, 28, and 44. The method mayadditionally include controlling the flow of the resin during reflow byselecting for the resin a glass temperature higher than the ball gridarray's reflow temperature at Block 60. The method ends at Block 62.

In another method embodiment, which is now described with reference toflowchart 64 of FIG. 13, the method begins at Block 66. The method mayinclude the steps of FIG. 4 at Blocks 26 and 28. The method mayadditionally include positioning at least one of a resin and resin mixedwith dielectric constant materials where the magnetic underfill isundesirable at Block 68. The method ends at Block 70.

In another method embodiment, which is now described with reference toflowchart 72 of FIG. 14, the method begins at Block 74. The method mayinclude the steps of FIG. 4 at Blocks 26 and 28. The method mayadditionally include curing the magnetic underfill using at least one ofthermal curing, infrared curing, and ultraviolet curing at Block 76. Themethod ends at Block 78.

In another method embodiment, which is now described with reference toflowchart 80 of FIG. 15, the method begins at Block 82. The method mayinclude the steps of FIG. 4 at Blocks 26 and 28. The method mayadditionally include cleaning any residue from the ball grid array'exposed surface after the conductive connection at Block 84. The methodends at Block 86.

In one embodiment, the system 10 includes ball grid array pads 12 a-12n, a coreless package 20, and a ball grid array 14 carried by thecoreless package. In another embodiment, the system 10 includesconnection members 16 a-16 n of the ball grid array 14 conductivelyconnected to respective ball grid array pads 12 a-12 n. In oneembodiment, the system 10 includes magnetic underfill 18 a-18 npositioned adjacent at least some of the connection members 16 a-16 nand respective ball grid array pads 12 a-12 n to increase respectiveconnection members' inductance, and the magnetic underfill is appliedbased upon the ball grid array's 14 height after collapse.

In another embodiment, the system 10 includes ball grid array pads 12a-12 n, a coreless package 20, and a ball grid array 14 carried by thecoreless package. In one embodiment, the system 10 includes connectionmembers 16 a-16 n of the ball grid array 14 conductively connected torespective ball grid array pads 12 a-12 n. In another embodiment, thesystem 10 includes magnetic underfill 18 a-18 n positioned adjacent atleast some of the connection members 16 a-16 n and respective ball gridarray pads 12 a-12 n to increase respective connection members'inductance. In one embodiment, the system 10 includes resin and/or resinmixed with dielectric constant materials 21 a″-21 n″ positioned wherethe magnetic underfill 18 a-18 n is undesirable.

In view of the foregoing, the system 10 improves core packageconnections. As a result, the system 10 improves signal integrity ofhigh-speed signals by reducing the impedance discontinuity between theball grid array 14 and ball grid array pads 12 a-12 n, for example.

For instance, extra capacitance associated with a ball grid array mayintroduce impedance discontinuity and cause detrimental effect onsignals transmitted via such. In addition, coreless packages do not havea thick core that can be used to reduce ball grid array pads'capacitance. However, system 10 addresses these problems.

In one embodiment, ferrite powders are mixed with epoxy resin materialto form a mixture with a desired permeability. In another embodiment,the permeability of the mixture depends on the ferrite material and theamount of it. For example, doped Yttrium-Iron-Garnet (YIG) materialshave a range of permeabilities to choose from. In one embodiment, whenlight magnetic doping is needed, ferromagnetic materials are used.

In one embodiment, after a chip is packaged and ball grid arrays 14 areadded, certain amounts of this mixture is applied between connectionmembers 16 a-16 n of the ball grid arrays 14. In another embodiment, theamount of the mixture that is applied is determined by the ball gridarray 14 height after collapse and/or the like. In one embodiment, thepackaged chip with the ball grid array 14 underfill is reflowed to asystem board.

In one embodiment, the magnetic underfill 18 a-18 n will increase theinductance of the ball grid array 14 by m times, where m is theeffective permeability of the mixture material. In another embodiment, mcan be easily adjusted to cover a wide range of permeabilities.

In one embodiment, the increased inductance will offset the extracapacitance from ball grid array 14 and ball grid array pads 12 a-12 n,and therefore it will decrease impedance discontinuity. In anotherembodiment, since permeability of the mixture can be changed by changingferrite materials, or the amount of such, an optimal case can beachieved that substantially compensates for the extra capacitance.

In one embodiment, the system 10 is implementable with corelesspackages. In another embodiment, if higher inductance is needed, moreferrite powders or powders with higher permeability can be used.

In one embodiment, screening epoxy resin based materials can be donewith standard screening processes, and other manufacturing steps are thesame as the standard procedures. In another embodiment, screen lowviscosity filled material on the bottom side of the package followingplace and reflow of the ball grid array 14 balls.

In one embodiment, a low to mild pressure from the squeeze is acceptablesince the application of the material does not have to be very even. Inanother embodiment, and depending on the material, a quick cure step,e.g. thermal, IR, or UV, may be employed to improve the set up of thematerial. In one embodiment, a plasma cleaning or wash may be employedto remove any residue from the exposed surface of the ball grid array 14ball prior to final test and ship of the component.

In one embodiment, the system 10 would require a screen design with anopening in the center of the ball grid array 14 field where power andground ball grid array's are typically located. In another embodiment,the system 10 would require the screening process outlined for thepreceding embodiment along with a second screening process where amaterial without the magnetic filler, e.g. resin mixed with dielectricconstant materials 21 a″-21 n″, which would be screened in the center ofthe part and surround the power and ground of the ball grid array 14.The filler in the center material may include high dielectric such asBarium Titanate (“BaTi03”) for improved decoupling in the power andground distribution in the package.

In one embodiment, magnetic underfill 18 a-18 n is applied in the entireball grid array 14 area. Such may be a one step screening process. Inanother embodiment, magnetic underfill 18 a-18 n is applied in certainareas, e.g., high speed signal area, but not other areas, e.g. powersupplies. Such may be a one step screening process. In one embodiment,it will require the epoxy resin to have a glass temperature higher thanball grid array 14 reflow temperature, so that the mixture materialswill not spread during reflow.

In one embodiment, magnetic underfill 18 a-18 n is applied in certainareas, e.g. high speed signal areas. In other areas, epoxy “as is” orepoxy mixed with high dielectric constant materials 21 a″-21 n″ areapplied to areas such as the power supply area. The foregoing may be atwo (or multiple) step process. In another embodiment, when an epoxymixed with a high dielectric constant materials 21 a″-21 n″ is used, anextra benefit from increased capacitance for the power supply can beachieved. In one embodiment, there is no need to require epoxy resin tohave glass temperature higher than the ball grid array 14 reflowtemperature.

As will be appreciated by one skilled in the art, aspects of theinvention may be embodied as a system, method or computer programproduct. Accordingly, aspects of the invention may take the form of anentirely hardware embodiment, an entirely software embodiment (includingfirmware, resident software, micro-code, etc.) or an embodimentcombining software and hardware aspects that may all generally bereferred to herein as a “circuit,” “module” or “system.” Furthermore,aspects of the invention may take the form of a computer program productembodied in one or more computer readable medium(s) having computerreadable program code embodied thereon.

Any combination of one or more computer readable medium(s) may beutilized. The computer readable medium may be a computer readable signalmedium or a computer readable storage medium. A computer readablestorage medium may be, for example, but not limited to, an electronic,magnetic, optical, electromagnetic, infrared, or semiconductor system,apparatus, or device, or any suitable combination of the foregoing. Morespecific examples (a non-exhaustive list) of the computer readablestorage medium would include the following: an electrical connectionhaving one or more wires, a portable computer diskette, a hard disk, arandom access memory (RAM), a read-only memory (ROM), an erasableprogrammable read-only memory (EPROM or Flash memory), an optical fiber,a portable compact disc read-only memory (CD-ROM), an optical storagedevice, a magnetic storage device, or any suitable combination of theforegoing. In the context of this document, a computer readable storagemedium may be any tangible medium that can contain, or store a programfor use by or in connection with an instruction execution system,apparatus, or device.

A computer readable signal medium may include a propagated data signalwith computer readable program code embodied therein, for example, inbaseband or as part of a carrier wave. Such a propagated signal may takeany of a variety of forms, including, but not limited to,electro-magnetic, optical, or any suitable combination thereof. Acomputer readable signal medium may be any computer readable medium thatis not a computer readable storage medium and that can communicate,propagate, or transport a program for use by or in connection with aninstruction execution system, apparatus, or device.

Program code embodied on a computer readable medium may be transmittedusing any appropriate medium, including but not limited to wireless,wireline, optical fiber cable, RF, etc., or any suitable combination ofthe foregoing.

Computer program code for carrying out operations for aspects of thepresent invention may be written in any combination of one or moreprogramming languages, including an object oriented programming languagesuch as Java, Smalltalk, C++ or the like and conventional proceduralprogramming languages, such as the “C” programming language or similarprogramming languages. The program code may execute entirely on theuser's computer, partly on the user's computer, as a stand-alonesoftware package, partly on the user's computer and partly on a remotecomputer or entirely on the remote computer or server. In the latterscenario, the remote computer may be connected to the user's computerthrough any type of network, including a local area network (LAN) or awide area network (WAN), or the connection may be made to an externalcomputer (for example, through the Internet using an Internet ServiceProvider).

Aspects of the invention are described below with reference to flowchartillustrations and/or block diagrams of methods, apparatus (systems) andcomputer program products according to embodiments of the invention. Itwill be understood that each block of the flowchart illustrations and/orblock diagrams, and combinations of blocks in the flowchartillustrations and/or block diagrams, can be implemented by computerprogram instructions. These computer program instructions may beprovided to a processor of a general purpose computer, special purposecomputer, or other programmable data processing apparatus to produce amachine, such that the instructions, which execute via the processor ofthe computer or other programmable data processing apparatus, createmeans for implementing the functions/acts specified in the flowchartand/or block diagram block or blocks.

These computer program instructions may also be stored in a computerreadable medium that can direct a computer, other programmable dataprocessing apparatus, or other devices to function in a particularmanner, such that the instructions stored in the computer readablemedium produce an article of manufacture including instructions whichimplement the function/act specified in the flowchart and/or blockdiagram block or blocks.

The computer program instructions may also be loaded onto a computer,other programmable data processing apparatus, or other devices to causea series of operational steps to be performed on the computer, otherprogrammable apparatus or other devices to produce a computerimplemented process such that the instructions which execute on thecomputer or other programmable apparatus provide processes forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof code, which comprises one or more executable instructions forimplementing the specified logical function(s). It should also be notedthat, in some alternative implementations, the functions noted in theblock may occur out of the order noted in the figures. For example, twoblocks shown in succession may, in fact, be executed substantiallyconcurrently, or the blocks may sometimes be executed in the reverseorder, depending upon the functionality involved. It will also be notedthat each block of the block diagrams and/or flowchart illustration, andcombinations of blocks in the block diagrams and/or flowchartillustration, can be implemented by special purpose hardware-basedsystems that perform the specified functions or acts, or combinations ofspecial purpose hardware and computer instructions.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescription of the present invention has been presented for purposes ofillustration and description, but is not intended to be exhaustive orlimited to the invention in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the invention. Theembodiment was chosen and described in order to best explain theprinciples of the invention and the practical application, and to enableothers of ordinary skill in the art to understand the invention forvarious embodiments with various modifications as are suited to theparticular use contemplated.

While the preferred embodiment to the invention has been described, itwill be understood that those skilled in the art, both now and in thefuture, may make various improvements and enhancements which fall withinthe scope of the claims which follow. These claims should be construedto maintain the proper protection for the invention first described.

1. A system comprising: ball grid array pads; a ball grid array, theball grid array having a plurality of connection members; the connectionmembers of said ball grid array conductively connected to respectiveball grid array pads; and magnetic underfill positioned adjacent atleast some of said connection members and respective ball grid arraypads to increase respective connection members' inductance.
 2. Thesystem of claim 1 wherein said magnetic underfill comprises resin mixedwith magnetic materials.
 3. The system of claim 2 wherein said resincomprises epoxy and said magnetic material comprises at least one offerrite powder and ferromagnetic materials.
 4. The system of claim 2wherein the mixture is selected based upon a desired permeability. 5.The system of claim 1 wherein said magnetic underfill is applied basedupon said ball grid array's height after collapse.
 6. The system ofclaim 2 wherein said resin has a glass temperature higher than said ballgrid array's reflow temperature so flow of said resin can be controlledduring reflow.
 7. The system of claim 1 further comprising at least oneof resin and resin mixed with dielectric constant materials positionedwhere said magnetic underfill is undesirable.
 8. The system of claim 1wherein said ball grid array is carried by a coreless package.
 9. Amethod comprising: positioning magnetic underfill adjacent to at leastsome of connection members of a ball grid array and respective ball gridarray pads to increase the connection members' inductance; andconductively connecting the connection members of the ball grid array torespective ball grid array pads.
 10. The method of claim 9 furthercomprising applying the magnetic underfill based upon the ball gridarray's height after collapse.
 11. The method of claim 9 furthercomprising mixing resin with magnetic materials based upon a desiredpermeability to produce the magnetic underfill.
 12. The method of claim11 further comprising selecting at least one of ferrite powder andferromagnetic materials for the magnetic material.
 13. The method ofclaim 11 further comprising controlling the flow of the resin duringreflow by selecting for the resin a glass temperature higher than theball grid array's reflow temperature.
 14. The method of claim 9 furthercomprising positioning at least one of a resin and resin mixed withdielectric constant materials where the magnetic underfill isundesirable.
 15. The method of claim 9 further comprising curing themagnetic underfill using at least one of thermal curing, infraredcuring, and ultraviolet curing.
 16. The method of claim 9 furthercomprising cleaning any residue from the ball grid array' exposedsurface after the conductive connection.
 17. A system comprising: ballgrid array pads; a coreless package; a ball grid array carried by saidcoreless packaging; connection members of said ball grid arrayconductively connected to respective ball grid array pads; and magneticunderfill positioned adjacent at least some of said connection membersand respective ball grid array pads to increase respective connectionmembers' inductance, and said magnetic underfill applied based upon saidball grid array's height after collapse.
 18. The system of claim 17wherein said magnetic underfill comprises resin mixed with magneticmaterials.
 19. The system of claim 18 wherein said resin comprises epoxyand said magnetic material comprises at least one of ferrite powder andferromagnetic materials.
 20. The system of claim 18 wherein the mixtureis selected based upon a desired permeability.
 21. The system of claim18 wherein said resin has a glass temperature higher than said ball gridarray's reflow temperature so flow of said resin can be controlledduring reflow.
 22. The system of claim 17 further comprising at leastone of resin and resin mixed with dielectric constant materialspositioned where said magnetic underfill is undesirable.
 23. A systemcomprising: ball grid array pads; a coreless package; a ball grid arraycarried by said coreless packaging; connection members of said ball gridarray conductively connected to respective ball grid array pads;magnetic underfill positioned adjacent at least some of said connectionmembers and respective ball grid array pads to increase respectiveconnection members' inductance; and at least one of resin and resinmixed with dielectric constant materials positioned where said magneticunderfill is undesirable.
 24. The system of claim 23 wherein saidmagnetic underfill comprises resin mixed with magnetic materials. 25.The system of claim 24 wherein the mixture is selected based upon adesired permeability.